It is current practice in orthopedic surgery to use plate and/or rod systems for joining portions of a broken bone, or for fusion of portions of separate bones. Such systems are composed essentially of plates, rods and screws for aligning and holding the bone portions in a desired position relative to one another. Plate and rod systems have usefulness in the spine, and have general skeletal use on the flat surfaces of bones, such as the scapula and the pelvis by way of example, and for use on tubular bones, such as the humerus, radius, femur, and tibia.
Currently known plating systems present disadvantages to patients and surgeons as they do not contemplate and/or allow for mass transfer to and from a site directly below or surrounding the plate. Thus, conventional plates typically impede the regeneration and osteosynthesis of the bone or tissue they are intended to heal. Additional problems associated with plating systems have included hardware breakage, hardware loosening, insufficient flexibility particularly over time, inability to gain adequate fixation, unnecessary additional weight, and other problems related to implant and recovery of the patient. One particular problem is “distraction pseudoarthrosis” where the plate will not allow the bone portions to come together over time resulting in a failure to get solid bone healing. These occurrences may cause problems, be associated with surgical failure, and require further surgical procedures to repair the damage, remove the failed hardware, and/or to reattempt stabilization of the boney anatomy.
Plates and rods are usually provided to the surgeon for use in sets having a range of sizes so as to provide for such features as biological variability in size, the numbers of segments to be joined, and the length of the portions of bone to be joined. By way of example, it would be common for a plating system for use on the anterior cervical spine and for joining from two to five vertebrae to comprise of from forty to sixty plates. This requires manufacturers to make a large number of different plates, resulting in increased manufacturing costs and inventory costs and increased costs for hospitals to stock large numbers of plates. Further, in the event that a plate is used and another of its kind is needed before it can be replaced, the ability to provide to a patient the best care could be compromised.
Known plate and rod systems additionally experience problems in connection with those procedures where bone grafts are placed between vertebral bodies to achieve an interbody fusion which heals by a process called “creeping substitution.” In this process, dead bone at the interfaces between the graft and the adjacent vertebra is removed by the body, as a prelude to the new growth of bone forming cells and the deposition of new bone. While the plates and rods allow for proper alignment of the vertebrae and their rigid fixation, they can therefore, at the same time unfortunately, hold the vertebrae apart while the resorption phase of the creeping substitution process forms gaps in the bone at the fusion site with the result that the desired fusion does not occur. Such failure in an attempted fusion is known as pseudoarthrosis. A similar phenomenon occurs at the interface of a fractured bone's fragments and is known as non-union. When such a failure occurs, the hardware itself will usually break or become loosened over time requiring further surgery to remove the broken hardware and to again attempt fusion or fracture repair.
There has been a long-felt and unmet need for an implant system which provides for required levels of strength, shock absorption, resistance to stresses and strain, and yet still allows for compliance and flexibility in order to wrap or accommodate various non-planar implant sites, while still allowing for adequate mass transfer to and from the implant site.